The present invention generally relates to air diffusers and, in a preferred embodiment thereof, more particularly relates to an air diffuser incorporating therein apparatus for automatically changing its air delivery pattern in response to changes in temperature of air being supplied to the diffuser.
Heating, ventilating and air conditioning (HVAC) units are conventionally utilized to supply heated or cooled air to the various rooms of a building as needed by the rooms to keep them at a desired temperature. The heated or cooled air is typically delivered to the rooms via a supply ductwork system interconnected between the HVAC unit(s) and a series of ceiling supply diffusers in the rooms to be maintained at a predetermined temperature. The supply air delivered to the rooms through the supply ductwork system is forced downwardly into the rooms through their associated ceiling supply diffusers, and is then flowed back to the HVAC unit(s), typically via a return ductwork system, to be reheated or recooled as necessary and flowed back into the rooms.
As is well known in the HVAC industry, the most effective manner of distributing air from ceiling diffusers during cooling is to direct the air in a generally horizontal flow across the ceiling of the room by employing what is known in the industry as the "Coanda effect." A stream of air discharged from a ceiling diffuser at an angle less than approximately 35 to 40 degrees with respect to the ceiling will tend to create a partial vacuum between the air and the ceiling and thereby cause the discharged air stream to remain in contact with or hug the ceiling as a result of the Coanda effect. Cool air, therefore, can be distributed over a substantial area of the ceiling by employing the Coanda effect before the cool air discharged from the ceiling diffuser begins to sink down into the room to cool the entire volume of the room.
On the other hand, the best efficiency in connection with the distribution of hot air from a ceiling diffuser is for the air to be discharged from the diffuser in a generally vertically oriented stream. The vertical flow component imparted to the heated air overcomes the natural buoyancy of the heated discharge air to serve the lower strata of the room with heated air and to thereby achieve a proper mixing of the heated air with the room air. Because the discharged air flows through the occupied space before mixing is complete, drafts may be directed at the occupants. However, most people do not perceive warm drafts as uncomfortable.
To avoid the considerable inconvenience of having to manually adjust the diffusers in a given HVAC system each time a heating/cooling changeover is required by the sensed room temperatures, various types of ceiling diffusers have been previously proposed in which their air discharge patterns are automatically changed in response to a sensed change in the temperature of air being delivered thereto by an HVAC unit. Various motorized and non-motorized structures have been associated with ceiling diffusers to effect this desired change in air discharge patterning in response to a sensed changeover from heating air to cooling air, and vice versa, being supplied to the diffuser.
However, conventional heating/cooling air patterning changeover apparatus used in conjunction with ceiling diffusers has tended to be undesirably expensive, complex, unreliable and/or relatively difficult to install. Accordingly, it is an object of the present invention to provide a ceiling diffuser with improved heating/cooling air patterning changeover apparatus that eliminates or at least substantially eliminates these problems, limitations and disadvantages associated with conventional thermal changeover apparatus.